Animator Controller Asset

Use an Animator ControllerControls animation through Animation Layers with Animation State Machines and Animation Blend Trees, controlled by Animation Parameters. The same Animator Controller can be referenced by multiple models with Animator components. More info
See in Glossary asset to maintain a set of animations for a character or object.

Animator Controller assets are created from the Assets menu, or from the Create menu in the Project windowA window that shows the contents of your Assets folder (Project tab) More info
See in Glossary.

In most situations, it’s normal to have multiple animations and transition between them when certain game conditions occur. For example, you could transition from a walk animation to a jump whenever the spacebar is pressed. However, even if you just have a single animation clipAnimation data that can be used for animated characters or simple animations. It is a simple “unit” piece of motion, such as (one specific instance of) “Idle”, “Walk” or “Run”. More info
See in Glossary, you still need to place it into an Animator Controller to use it on a Game Object.

The Animator Controller has references to the Animation clips it uses. The Animator Controller manages the various Animation Clips and the Transitions between them using a State MachineThe set of states in an Animator Controller that a character or animated GameObject can be in, along with a set of transitions between those states and a variable to remember the current state. The states available will depend on the type of gameplay, but typical states include things like idling, walking, running and jumping. More info
See in Glossary, which could be thought of as a flow-chart of Animation Clips and Transitions. You can find more information about state machines here.

Unity automatically creates an Animator Controller when you begin animating a GameObjectThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary using the Animation Window, or when you attach an Animation Clip to a GameObject.

To manually create an Animator Controller, right-click within either column of the Project window and select Create > Animator Controller.